The present invention relates to a process for the preparation of substituted 3-(1-amino-2-methylpentane-3-yl)phenyl compounds.
A class of active ingredients having excellent analgesic effectiveness and very good tolerability are substituted 3-(1-amino-2-methylpentane-3-yl)phenyl compounds such as for example (3-(3-methoxyphenyl)-2-methyl-pentyl)dimethylamine which are inter alia known from EP 0 693 475 B1 and WO 2008/012047 A1.

These compounds are conventionally prepared via a multi-step synthesis including a Mannich reaction as one of the key steps as it is exemplarily depicted below for the synthesis of (3-(3-methoxyphenyl)-2-methyl-pentyl)dimethylamine:
